Not applicable.
The invention relates to safety and security covers of new and existing ventilation ducts (xe2x80x9cventsxe2x80x9d) for tanks, buildings, and other infrastructure.
Tanks, buildings, and other infrastructure which are vented to the atmosphere are subject to intentional threats and acts of sabotage by vandals or more recently by terrorists through the venting system. Sabotage may include introduction of liquids, gases or solids containing hazardous chemical, biological, or radiological agents into tanks, buildings, and other infrastructure through these vents. The vents common to such tanks, buildings, and other infrastructure are vulnerable to such attacks need a security and alarm system to deny or impede unauthorized access and to alert authorities if an intrusion occurs.
U.S. Pat. No. 4,593,504 discloses a pressure equalizing roof vent. The vent includes apertures near the upper end of a tube. These apertures allow air to exit the tube. However, the apertures are easily tampered with since they are merely covered by a cap which is easily removed.
U.S. Pat. No. 5,694,724 discloses a stacking vent cover. The vent cover does not prevent gases, liquids or solids from being placed down the vent. The vent is open to the atmosphere and tampering is relatively easy, including simply dropping something down the vent.
U.S. Pat. No. 5,816,288 discloses a protective vent cover. The vent is protected by having an inner flexible screen wrapped by an outer heavier more rigid screen. The screens protect the vent from insects and frost. However, the vent is easy to tamper with by simply cutting through the screens which are not protectively covered.
Similar vent covers are known; however, access to the vent is not restricted. Therefore there is a need for a vent cover that would protect the vent from tampering while still being operable.
The invention to accomplish this protection is a security cover for vents on tanks, building, and other infrastructure. The security cover of this invention may be an add-on fixture to existing vents or as the venting system of a new structure. The configuration of the security cover creates a tortuous path between the interior of the structure and the outside atmosphere, making it difficult for an intruder to introduce a hazardous liquid, gas, or solid material through the vent to invade the interior of the structure. The tortuous path accomplished in the practice of this invention is created by the use of a series of cylindrical baffles which could be called additional pipes to the vent being protected concentrically arranged with an attached cover oriented such that air may enter from the atmosphere through openings proximate to the attached cover and be deflected downwardly by a second concentric baffle toward a base plate which in turn reverses the flow of the air upwardly adjacent a third concentric baffle which terminates with a means for allowing air to pass, such as an offset from the attached cover or openings in the cylindrical baffle, or pipe, allowing the gases to enter the vent on the structure being protected. Of course in instances where pressure inside the tank is greater than the outside pressure, the flow is in the opposite direction. As an optional feature of the interior, an adjustable deflector cone may be attached to the cover cap and over the opening into the structure. In a new structure, the vent pipe for the structure may be constructed integrally with the cylindrical baffles, or pipes, used to create the tortuous path, thus eliminating the need for parts to attach the safety vent to the structure. Of course the description above and later will be made in terms of cylindrical pipes and baffles, it being understood that regardless of the cross-sectional geometry of the vent on the structure being protected, whether retrofit or new construction, the apparatus of this invention can be adapted to fit such cross-sectional geometry.
The security cover is optionally equipped with an alarm system which creates an audible alarm or a transmitter, hardwired or wireless, to arouse protection from a remote location, or both. In the event the security cover is cut or removed, an alarm sounds, a light flashes, and an alert is sent to a remote receiver. Any one or all of these events may occur. The security cover is secured in place using a custom set plate attached to the commonly present vent pipe on existing structures. The set plate has a hasp assembly to accommodate shrouded padlocks or other fasteners of more permanent nature such as, for example, rivets or welded attachment.
Several other design factors are important. The security vent cannot compromise the function of the vent to accommodate suitable air flow. The vent shroud should be made of a material suitable for installation outdoors subject to typical weather conditions on existing or new vents without interfering with operations to the building, tank, or other infrastructure. Finally, the security cover should be readily detachable and reusable.